Refrigerant compressor

ABSTRACT

A refrigerant compressor forms a refrigerant circulation circuit with an external refrigerant circuit, and includes an oil separation structure. The oil separation structure includes a plurality of separation chambers for centrifugally separating oil from refrigerant gas, an oil storage chamber for storing the oil separated in the plurality of separation chambers, a connection passage and an oil passage. The plurality of separation chambers and the oil storage chamber are recessed within thickness of a circumferential wall of a housing component so as to be juxtaposed in a transverse direction passing across the housing component. The connection passage connects the plurality of separation chambers, and extends in the transverse direction along the refrigerant gas flow in a discharge path. The oil passage connects the oil storage chamber and the separation chambers, and extends in the transverse direction.

BACKGROUND OF THE INVENTION

The present invention relates to a refrigerant compressor including an oil separation structure for separating lubricant oil from refrigerant gas on a discharge path from a compression mechanism to an external refrigerant circuit.

A refrigerant compressor in vehicle air conditioners forms a refrigerant circulation circuit with the external refrigerant circuit, and smoothly operates a compression mechanism by adding lubricant oil (refrigeration oil) to refrigerant gas and supplying the oil to the compression mechanism. The refrigerant compressor includes an oil separation structure provided on the discharge path of refrigerant gas for preventing the oil from the flowing out to the external refrigerant circuit with the refrigerant gas (for example, refer to Japanese Patent Application Publication No. 2000-2183). If the oil flows out to the external refrigerant circuit, the oil adheres to the inner wall surface of a condenser or an evaporator in the external refrigerant circuit to deteriorate the heat exchange efficiency in the external refrigerant circuit.

The oil separation structure disclosed in Japanese Patent Application Publication No. 2000-2183 is provided in a rear housing constituting the housing of the refrigerant compressor. Specifically, an accommodating chamber is formed on the discharge path in the rear housing, and a partition is incorporated in the accommodating chamber. The partition divides the accommodating chamber into a separation chamber for oil separation and a communication chamber connected with the separation chamber by a communication passage. The separation chamber is connected with a discharge chamber for refrigerant gas by an introduction passage in the rear housing, and also with a crank chamber within the refrigerant compressor by a supply passage in the rear housing. The communication chamber is connected with a muffler chamber by a delivery passage formed in the rear housing, the muffler chamber being connected with the external refrigerant circuit.

In the oil separation structure disclosed in Japanese Patent Application Publication No. 2060-2183, refrigerant gas discharged to the discharge chamber is introduced to the separation chamber through the introduction passage, and swirls along the inner circumferential surface in the separation chamber. The oil mist contained in the refrigerant gas is then separated by centrifugal force. The refrigerant gas after oil separation is delivered to the external refrigerant circuit through the communication passage, the communication chamber, the delivery passage and the muffler chamber. The oil separated in the separation chamber is supplied to the crank chamber through the supply passage, with the refrigerant gas for displacement control of the refrigerant compressor. The oil supplied to the crank chamber is supplied to each sliding part within the refrigerant compressor and exhibits lubricating and cooling effects therein.

In such a refrigerant compressor, further reduction in the lubricant oil flowing out to the external refrigerant circuit is strongly demanded, and the reduction in the outflow of the oil seriously requires improvement in oil separation capability in the oil separation structure. In the oil separation structure of Japanese Patent Application Publication No. 2000-2183, it is conceivable to ensure a sufficient swirling distance of refrigerant gas in the separation chamber for the improvement in oil separation capability. A radially or axially enlarged separation chamber (accommodating chamber) may be formed in the rear housing to ensure the sufficient swirling distance of refrigerant gas. This enlargement of the rear housing results in increase in size of the refrigerant compressor.

The present invention is directed to a refrigerant compressor capable of improving oil separation capability without enlargement of the size thereof.

SUMMARY OF THE INVENTION

In accordance with an aspect of the present invention, a refrigerant compressor forms a refrigerant circulation circuit with an external refrigerant circuit. The refrigerant compressor includes a housing, a compression mechanism and an oil separation structure. The housing has a plurality of housing components joined together. The compression mechanism is provided in the housing, which draws refrigerant gas from the external refrigerant circuit for compression and discharges the compressed refrigerant gas thereto. The oil separation structure is provided on a discharge path of the refrigerant gas flowing from the compression mechanism toward the external refrigerant circuit for separating oil contained in the refrigerant gas. The oil separation structure includes a plurality of separation chambers for centrifugally separating the oil from the refrigerant gas, an oil storage chamber for storing the oil separated in the plurality of separation chambers, a connection passage and an oil passage. The plurality of separation chambers and the oil storage chamber are recessed within thickness of a circumferential wall of one of the housing components so as to be juxtaposed in a transverse direction passing across the housing component. The connection passage connects the plurality of separation chambers, and extends in the transverse direction along the refrigerant gas flow in the discharge path. The oil passage connects the oil storage chamber and the separation chambers, and extends in the transverse direction.

Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the present invention that are believed to be novel are set forth with particularity in the appended claims. The invention together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

FIG. 1 is a longitudinal sectional view showing a compressor according to an embodiment of the present invention;

FIG. 2 is a partial cross sectional view showing an oil separation structure of the compressor;

FIG. 3 is a cross sectional view as seen from the line III-III of FIG. 2 showing the oil separation structure; and

FIG. 4 is a partial cross sectional view showing another oil separation structure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of a variable displacement swash plate compressor for vehicle air conditioners according to the refrigerant compressor of the present invention will now be described with reference to FIGS. 1 to 3. In the following description, the direction of arrow Y1 shown in FIG. 1 corresponds to the “front” and “rear” (longitudinal) direction of the variable displacement swash plate compressor, and the direction of arrow Y2 shown in FIG. 2 corresponds to the “upper” and “lower” (vertical) direction thereof.

As shown in FIG. 1, the housing of the variable displacement swash plate compressor (hereinafter referred to simply as a “compressor”) 10 includes a cylinder block 11, a front housing 12 fixedly joined to a front end of the cylinder block 11, and a rear housing 13 fixedly joined to a rear end of the cylinder block 11 through a valve plate assembly 14. Each of the cylinder block 11, the front housing 12 and the rear housing 13 serves as a housing component. The cylinder block 11 has a cylindrical shape and a substantially cylindrical wall or an outer circumferential wall 40. A plurality of cylinder bores 11 a are formed in the cylinder block 11 in the longitudinal direction of the compressor 20. The front housing 12 has a cylindrical shape bottomed at the front end thereof, and the rear housing 13 has a cylindrical shape covered at the rear end thereof.

The cylinder block 11 and the front housing 12 rotatably support a rotary shaft 16. The rotary shaft 16 is connected to a vehicle engine through a clutch mechanism such as an electromagnetic clutch, and the rotary shaft 16 is driven by the vehicle engine through the clutch mechanism when the vehicle engine is operated.

The cylinder block 11 and the front housing 12 form a crank chamber 15. In the crank chamber 15, a rotary support 19 is fixedly mounted on the rotary shaft 16 so as to be integrally rotatable with the rotary shaft 16. In the crank chamber 15, the rotary shaft 16 supports a swash plate 20 so as to be slidable and tiltable in the axial direction of the rotary shaft 16. A hinge mechanism 21 is interposed between the rotary support 19 and the swash plate 20, and enables the swash plate 20 to tilt relative to the rotary shaft 16 and integrally rotate with the rotary shaft 16. In the cylinder block 11, the cylinder bores 11 a are formed through the cylinder block 11 at equal intervals around the rotary shaft 16, and each cylinder bore 11 a accommodates a single-headed piston 22. One end of each cylinder bore 11 a is closed by the front surface of the valve plate assembly 14. The rear end surface of the associated piston 22 and the front surface of the valve plate assembly 14 form a compression chamber (not shown) in each cylinder bore 11 a. The volume of the compression chamber is changed according to reciprocation of the associated piston 22. Each piston 22 is connected to an outer peripheral portion of the swash plate 20 through a pair of shoes 30 to convert rotating motion of the swash plate 20 to reciprocating linear motion of the piston 22 through the shoes 30.

The rear surface of the valve plate assembly 14 and the rear housing 13 form a suction chamber 23 and a discharge chamber 24. The valve plate assembly 14 has a plurality of suction ports 25 and suction valves 26 in correspondence with each piston 22. The refrigerant gas in the suction chamber 23 is drawn into the compression chamber through the suction port 25 and the suction valve 26 by movement from top dead center toward bottom dead center of each piston 22 associated with rotation of the rotary shaft 16. The valve plate assembly 14 has a plurality of discharge ports 27 and discharge valves 28 in correspondence with each piston 22. The refrigerant gas drawn into the compression chamber is compressed to a predetermined pressure by movement from bottom dead center toward top dead center of the piston 22 associated with rotation of the rotary shaft 16, and discharged to the discharge chamber 24 through the discharge port 27 and the discharge valve 28. The rotary shaft 16, the rotary support 19, the swash plate 20, the piston 22 and the compression chamber form a compression mechanism within the housing of the compressor 10.

A cover 51 is coupled with an upper portion of the circumferential wall 40 of the cylinder block 11 through a gasket 50. A muffler chamber 17 a is formed by the cover 51 and the gasket 50. As shown in FIGS. 2 and 3, an oil separation structure S is provided under the muffler chamber 17 a on the circumferential wall 40 of the cylinder block 11. The refrigerant gas is introduced into the oil separation structure S for oil separation and is discharged to the muffler chamber 17 a. An introduction passage 18 is formed in the valve plate assembly 14 and the cylinder block 11 to connect the discharge chamber 24 to the oil separation structure S. The refrigerant gas discharged to the discharge chamber 24 from the compression mechanism is introduced into the oil separation structure S through the introduction passage 18.

A refrigerant circulation circuit for vehicle air conditioners is composed of the compressor 10 and an external refrigerant circuit 29. The external refrigerant circuit 29 includes a condenser 29 a, an expansion valve 29 b and an evaporator 29 c. A refrigerant passage 39 connects the muffler chamber 17 a to the condenser 29 a of the external refrigerant circuit 29. The pressure pulsation of the refrigerant gas discharged to the muffler chamber 17 a is attenuated by an expansion type muffler effect of the muffler chamber 17 a. The discharge chamber 24, the introduction passage 18, the oil separation structure S, the muffler chamber 17 a and the refrigerant passage 39 form a discharge path for passing the refrigerant gas discharged from the compression mechanism and delivered to the external refrigerant circuit 29. The refrigerant gas discharged to the muffler chamber 17 a flows to the condenser 29 a, the expansion valve 29 b, the evaporator 29 c, and is drawn to the compression mechanism through the suction chamber 23.

A bleed passage 32, a supply passage 33 and a control valve 34 are provided within the housing of the compressor 10. The bleed passage 32 includes a passage 32 a formed in the axial center of the rotary shaft 16 and a through hole 32 b formed in the cylinder block 11 and the valve plate assembly 14, and connects the crank chamber 15 to the suction chamber 23. The supply passage 33 connects the discharge chamber 24 to the crank chamber 15, and the control valve 34 is disposed in the supply passage 33. The difference between the amount of the high-pressure discharge gas introduced to the crank chamber 15 through the supply passage 33 and the amount of the refrigerant gas flowing out from the crank chamber 15 through the bleed passage 32 is controlled by adjusting the opening size of the control valve 34, and the pressure in the crank chamber 15 is determined. The difference between the pressure in the crank chamber 15 and the pressure in the compression chamber is changed in accordance with change in pressure in the crank chamber 15, and the inclination angle of the swash plate 20 is changed. As a result, the stroke of the piston 22 or the displacement of the compressor 10 is adjusted.

The oil separation structure S of the compressor 10 will then be described. As shown in FIGS. 1 and 2, the circumferential wall 40 of the cylinder block 11 is formed in a substantially cylindrical shape around the rotary shaft 16 so as to have a predetermined thickness on the outer circumferential side of each cylinder bore 11 a. The circumferential wall 40 has a square pole-like projecting portion 40 a under the cover 51 through the gasket 50. The oil separation structure S is provided in the projecting portion 40 a. The projecting portion 40 a is a connecting part to be connected with the cover 51 so as to form the muffler chamber 17 a. Thus, the oil separation structure S is provided using the existing projecting portion 40 a, not adding a special part.

As shown in FIGS. 2 and 3, the projecting portion 40 a of the cylinder block 11 is provided with a first separation chamber 41, a second separation chamber 42, and an oil storage chamber 43, which are vertically recessed. The separation chambers 41, 42 and the oil storage chamber 43 constitute the oil separation structure S. The gasket 50 closes the openings of the first separation chamber 41 and the oil storage chamber 43 at the upper surface of the projecting portion 40 a. The first separation chamber 41, the second separation chamber 42 and the oil storage chamber 43 are recessed within the thickness of the circumferential wall 40 (projecting portion 40 a) of the cylinder block 11, and juxtaposed in the transverse, or horizontal direction, viewed from the front end of the compressor 10. The transverse direction indicates the direction to linearly pass across an outer peripheral portion of the cylinder block 11 where the cylinder bores 11 a are not located. The second separation chamber 42 is disposed next to the first separation chamber 41 in the transverse direction, and the oil storage chamber 43 is disposed next to the second separation chamber 42 in the transverse direction. Preferably, the separation chambers 41, 42 and the oil storage chamber 43 are located in horizontal direction when the compressor 10 is installed in the refrigeration circulation circuit. The second separation chamber 42 is provided so as to be located slightly closer to the front side than the first separation chamber 41.

The first separation chamber 41 is provided on the downstream side of the discharge chamber 24 (compression mechanism) along the direction of refrigerant gas flow in the discharge path and centrifugally separates the oil contained in the refrigerant gas. An inner circumferential surface 41 a of the first separation chamber 41 is formed cylindrically with a circular section. An opening or an outlet 18 a of the introduction passage 18 is opened on the inner circumferential surface 41 a of the first separation chamber 41. The outlet 18 a of the introduction passage 18 is formed in a position closer to the second separation chamber 42 than the first axis L1 of the first separation chamber 14. The introduction passage 18 linearly extends from the discharge chamber 24 to the first separation chamber 41 in the axial direction of the rotary shaft 16. Therefore, the refrigerant gas flowing in the introduction passage 18 is introduced to the first separation chamber 41 through the outlet 18 a so as to flow along the inner circumferential surface 41 a of the first separation chamber 41. The refrigerant gas introduced to the first separation chamber 41 swirls along the inner circumferential surface 41 a, whereby the oil mist contained in the refrigerant gas is separated by the centrifugal force.

As shown by the two-dot chain line of FIG. 2 and the dash line of FIG. 3, a first oil passage 44 extends in the transverse direction. The first separation chamber 41 communicates with the oil storage chamber 43 through the first oil passage 44. A first oil inlet 44 a or one opening of the first oil passage 44 is opened on the inner circumferential surface 41 a of the first separation chamber 41, and a first oil outlet 44 b or the other opening thereof is opened to the oil storage chamber 43. The oil separated from the refrigerant gas in the first separation chamber 41 is introduced to the first oil passage 44 through the first oil inlet 44 a, and discharged to the oil storage chamber 43 through the first oil outlet 44 b. The first oil inlet 44 a is formed on the bottom side of the first separation chamber 41 and located below the outlet 18 a of the introduction passage 18.

The second separation chamber 42 is provided on the downstream side of the first separation chamber 41 in the direction of refrigerant gas flow in the discharge path to centrifugally separate the oil contained in the refrigerant gas. An inner circumferential surface 42 a of the second separation chamber 42 is formed cylindrically with a circular section. The second separation chamber 42 is connected with the muffler chamber 17 a through a through-hole 50 a formed in the gasket 50. A swirling flow forming member 45 is press-fitted to the upper side of the second separation chamber 42. The swirling flow forming member 45 is formed by a cylinder 45 a and a flange 45 b integrally formed therewith. The cylinder 45 a has a diameter smaller than that of the inner circumferential surface 42 a of the second separation chamber 42. The flange 45 b radially extends from the upper end of the cylinder 45 a. The flange 45 b has a diameter slightly larger than that of the second separation chamber 42.

The cylinder 45 a side of the swirling flow forming member 45 is inserted into the second separation chamber 42, and the peripheral end of the flange 45 b is pressed onto the inner circumferential surface 42 a of the second separation chamber 42, whereby the swirling flow forming member 45 is fixedly accommodated in the second separation chamber 42. In this accommodated state, the cylinder 45 a is disposed concentrically with the second axis 12 of the second separation chamber 42, and separated from the inner circumferential surface 42 a of the second separation chamber 42. An annular space is formed by the outer circumferential surface of the cylinder 45 a and the inner circumferential surface 42 a of the second separation chamber 42 so that refrigerant gas can be swirled therein. The second separation chamber 42 is divided from the muffler chamber 17 a by the flange 45 b. The second separation chamber 42 is connected with the muffler chamber 17 a through the inside of the cylinder 45 a.

A connection passage 46 is formed between the first separation chamber 41 and the second separation chamber 42 in the projecting portion 40 a to connect the first separation chamber 41 to the second separation chamber 42. The connection passage 46 is extended in the transverse direction. The first separation chamber 41 communicates with the second separation chamber 42 through the connection passage 46. One opening of the connection passage 46 is opened on the inner circumferential surface 41 a of the first separation chamber 41, and forms a gas inlet 46 a of refrigerant gas from the first separation chamber 41 to the connection passage 46. The other opening of the connection passage 46 is opened on the inner circumferential surface 42 a of the second separation chamber 42, and forms a gas outlet 46 b of refrigerant gas from the connection passage 46 to the second separation chamber 42. Namely, the refrigerant gas swirled in the first separation chamber 41 flows in the connection passage 46 and is delivered into the second separation chamber 42.

The gas inlet 46 a of the connection passage 46 is formed in a position closer to the second separation chamber 42 than the first axis L1 of the first separation chamber 41. Further, the gas outlet 46 b of the connection passage 46 is formed in a position closer to the first separation chamber 41 than the second axis L2 of the second separation chamber 42. The connection passage 46 is formed so as to linearly extend from the first separation chamber 41 to the second separation chamber 42. The gas inlet 46 a and gas outlet 46 b of the connection passage 46 are formed vertically higher than the outlet 18 a of the introduction passage 18, and the gas outlet 46 b is formed in a position opposed to the outer circumferential surface of the cylinder 45 a.

The second separation chamber 42 is connected to the oil storage chamber 43 by a second oil passage 47 extending in the transverse direction. A second oil inlet 47 a or one opening of the second oil passage 47 is opened on the inner circumferential surface 42 a of the second separation chamber 42, and a second oil outlet 47 b or the other opening thereof is opened to the oil storage chamber 43. The oil separated from the refrigerant gas within the second separation chamber 42 enters into the second oil passage 47 through the second oil inlet 47 a, and is discharged to the oil storage chamber 43 through the second oil outlet 47 b. Further, the oil storage chamber 43 is connected with the crank chamber 15 by an oil supply passage (not shown) formed in the cylinder block 11.

The refrigerant gas discharged to the discharge chamber 24 successively flows in the introduction passage 18, the first separation chamber 41, the connection passage 46, the second separation chamber 42 (in detail, the inside of the cylinder 45 a), and the muffler chamber 17 a, and is discharged to the external refrigerant circuit 29. Therefore, the discharge chamber 24, the introduction passage 18, the first separation chamber 41, the connection passage 46, the second separation chamber 42, and the muffler chamber 17 a form a discharge path in the housing of the compressor 10 for passing the refrigerant gas discharged from the compression mechanism to the external refrigerant circuit 29. The introduction passage 18, the first separation chamber 41, the second separation chamber 42, the oil storage chamber 43, the first oil passage 44, the connection passage 46, and the second oil passage 47, form the oil separation structure S for separating the oil contained in the refrigerant gas flowing from the discharge chamber 24 to the external refrigerant circuit 29 on the discharge path.

The oil separation mechanism by the oil separation structure S will then be described. The flow of refrigerant gas is shown by the two-dot chain line of FIG. 3. The refrigerant gas discharged to the discharge chamber 24 is introduced to the first separation chamber 41 through the introduction passage 18, and swirled along the inner circumferential surface 41 a in the first separation chamber 41. Then, the oil mist contained in the refrigerant gas is separated by the centrifugal force. In the inner circumferential surface 41 a of the first separation chamber 41, the outlet 18 a of the introduction passage 18 is located lower than the gas inlet 46 a of the connection passage 46. Therefore, the refrigerant gas introduced into the first separation chamber 41 through the outlet 18 a is introduced to the gas inlet 46 a not directly but after ascending while swirling along the inner circumferential surface 41 a. The oil separated from the refrigerant gas is collected on the bottom side of the first separation chamber 41 by its own weight. However, since the gas inlet 46 a of the connection passage 46 is located on the upper side in the inner circumferential surface 41 a, the oil collected in the first separation chamber 41 is hardly taken to the second separation chamber 42 through the connection passage 46.

The refrigerant gas which contains low amount of oil after the oil separation enters from the first separation chamber 41 into the connection passage 46 through the gas inlet 46 a, flows in the connection passage 46, and is then introduced to the second separation chamber 42 through the gas outlet 46 b and swirls along the cylinder 45 a and the inner circumferential surface 42 a of the second separation chamber 42. The oil mist which is not separated in the first separation chamber 41 and is still contained in the refrigerant gas, is separated by the centrifugal force. At this time, since the gas outlet 46 b of the connection passage 46 is formed opposing to the outer circumferential surface of the cylinder 45 a, the refrigerant gas delivered to the second separation chamber 42 is not introduced into the cylinder 45 a directly from the lower end of the cylinder 45 a, but introduced into the cylinder 45 a after descending while being forced to swirl around the cylinder 45 a. The refrigerant gas from which the oil is separated is discharged to the muffler chamber 17 a through the inside of the cylinder 45 a and further discharged to the external refrigerant circuit 29.

The oil separated in the first separation chamber 41 enters into the first oil passage 44 through the first oil inlet 44 a, and is discharged into the oil storage chamber 43 through the first oil outlet 44 b. The oil separated in the second separation chamber 42 enters into the second oil passage 47 through the second oil inlet 47 a, and is discharged into the oil storage chamber 43 through the second oil outlet 47 b. Consequently, the oil separated from the refrigerant gas is stored in the oil storage chamber 43. The oil stored in the oil storage chamber 43 is supplied to the crank chamber 15 through the oil supply passage due to the pressure difference between the first and second separation chambers 41, 42 (a discharge pressure area) and the crank chamber 15 (a low-pressure area). The oil supplied to the crank chamber 15 is supplied to each sliding part such as a connection part between the piston 22 and the shoe 30 or a connection part between the shoe 30 and the swash plate 20 to exhibit lubricating and cooling effects.

The illustrated embodiment has the following advantages.

(1) The first separation chamber 41, the second separation chamber 42 and the oil storage chamber 43 are arranged in the transverse direction to pass across the projecting portion 40 a within the thickness of the circumferential wall 40 of the cylinder block 11 (housing component), and the first separation chamber 41 and the second separation chamber 42 are connected by the connection passage 46 extending in the transverse direction. Therefore, while the refrigerant gas is passed through the first separation chamber 41 and the second separation chamber 42 and sent to the external refrigerant circuit 29, the oil contained in the refrigerant gas is centrifugally separated in the first separation chamber 41 and then further centrifugally separated in the second separation chamber 42. Accordingly, the swirling distance of the refrigerant gas on its path through the oil separation structure S becomes long, as compared to, for example, a case in which the refrigerant gas is swirled only within the first separation chamber 41. Thus, the oil separation capability can be improved. Although the two separation chambers 41 and 42 are provided in the circumferential wall 40 of the cylinder block 11 for extending the swirling distance of refrigerant gas, the thickness of the circumferential wall 40 is not increased since the two separation chambers 41 and 42 are not formed continuously in the thickness direction (vertical direction) of the circumferential wall 40, but juxtaposed in the transverse direction. Therefore, under the restriction of being within the thickness of the cylinder block 11, a long swirling distance of refrigerant gas can be ensured without enlarging the cylinder block 11, and improvement in oil separation capability can be attained without enlargement of the size of the compressor 10. (2) The first separation chamber 41, the second separation chamber 42 and the oil storage chamber 43 are provided within the thickness of the circumferential wall 40 of the cylinder block 11, and the connection passage 46 connecting the first separation chamber 41 to the second separation chamber 42 is formed so as to extend in the transverse direction. The first oil passage 44 and the second oil passage 47 connecting the separation chambers 41 and 42 to the oil storage chamber 43, respectively, are formed so as to extend in the transverse direction. Therefore, the oil separation structure S, which is improved in oil separation capability without enlargement of the cylinder block 11 by forming each passage 44, 46, 47 in the thickness direction (vertical direction) of the circumferential wall 40, can be provided without enlargement of the size of the compressor 10. (3) The first separation chamber 41 is provided within the thickness of the circumferential wall 40 of the cylinder block 11, and its depth is restricted. Therefore, if the oil separation structure S is composed of only the first separation chamber 41, the oil separated in the first separation chamber 41 is easily taken to the external refrigerant circuit 29. However, by providing the second separation chamber 42, the oil can be further separated in the second separation chamber 42 even if taken from the first separation chamber 41 to the second separation chamber 42 through the connection passage 46. Accordingly, the take-out of oil to the external refrigerant circuit 29 can be suppressed without increasing the depth of the separation chamber or enlarging the cylinder block 11. (4) The gas inlet 46 a of the connection passage 46 in the first separation chamber 41 is located on the upper side of the first separation chamber 41, so that the oil once stored in the first separation chamber 41 is hardly taken to the second separation chamber 42. (5) In the inner circumferential surface 41 a of the first separation chamber 41, the outlet 18 a of the introduction passage 18 and the gas inlet 46 a of the connection passage 46 are formed in different positions in the height direction. The gas inlet 46 a of the connection passage 46 is higher than the outlet 18 a of the introduction passage 18. Therefore, the refrigerant gas introduced to the first separation chamber 41 can be prevented from being immediately introduced to the gas inlet 46 a and delivered to the second separation chamber 42, as compared to a case in which the outlet 18 a of the introduction passage 18 is formed at the same height as the gas inlet 46 a of the connection passage 46. The swirling distance of the refrigerant gas in the first separation chamber 41 can be thus ensured to improve the oil separation capability. (6) The gas outlet 46 b of the connection passage 46 is formed in a position opposed to the outer circumferential surface of the cylinder 45 a. Therefore, the refrigerant gas delivered to the second separation chamber 42 can be prevented from being immediately discharged to the muffler chamber 17 a through the inside of the cylinder 45 a without swirling around the cylinder 45 a, as compared to a case in which the gas outlet 46 b is located lower than the cylinder 45 a. Namely, the refrigerant gas delivered to the second separation chamber 42 can be swirled around the cylinder 45 a, and the oil separation capability can be improved, as compared to a case in which the gas outlet 46 b is located lower than the cylinder 45 a. (7) The connection passage 46 is linearly formed in a position where the refrigerant gas swirling in the first separation chamber 41 can be delivered to the second separation chamber 42 without changing the direction of the swirling flow. Therefore, the flow velocity of the refrigerant gas delivered from the first separation chamber 41 to the second separation chamber 42 is not reduced, and the deterioration of oil separation capability resulted from reduction in flow velocity can be suppressed. (8) The connection passage 46 is formed in a position connecting the first separation chamber 41 to the second separation chamber 42 at a short distance. Therefore, the refrigerant gas can pass through the connection passage 46 without reduction in flow velocity, and the deterioration of oil separation capability resulted from reduction in flow velocity can be suppressed. (9) The cylinder 45 a is provided within the second separation chamber 42, and the refrigerant gas can be forcedly swirled by the cylinder 45 a. Therefore, the oil separation capability in the second separation chamber 42 can be improved as compared to a case in which the refrigerant gas swirls along the inner circumferential surface 42 a of the second separation chamber 42 without a cylinder, and almost all the oil contained in refrigerant gas is separated in the second separation chamber 42. Consequently, the take-out of oil to the external refrigerant circuit 29 can be substantially eliminated.

The above-mentioned embodiment of the present invention may be modified as follows.

In the above-mentioned embodiment, as shown in FIG. 4, a cylindrical or columnar separating portion 52 may be protrusively provided on the bottom surface of the first separation chamber 41, so that the refrigerant gas introduced in the first separation chamber 41 forcedly swirls around the separating portion 52.

The swirling flow forming member 45 may be eliminated from the second separation chamber 42, so that the oil is centrifugally separated only by swirling along the inner circumferential surface 42 a without the cylinder 45 a.

In the projecting portion 40 a of the cylinder block 11, three or more separation chambers may be provided along the transverse direction of the circumferential wall 40. In this case, the oil storage chamber 43 is narrowed, and the separation chambers successively arranged in the direction of refrigerant gas flow are connected by a connection passage so that the refrigerant gas is successively passed through each separation chamber.

The oil separation structure S may be provided on the circumferential wall of the front housing 12 or the rear housing 13 other than the cylinder block 11.

In the circumferential wall 40 of the cylinder block 11, the first separation chamber 41, the oil storage chamber 43 and the second separation chamber 42 may be successively provided in this order in the transverse direction.

The sectional area of the connection passage 46 or the introduction passage 18 can be set smaller than that in the embodiment as far as pressure loss permits, whereby the flow velocity of refrigerant gas from the passages is increased by the throttle effect to enhance the oil separation capability.

The compression mechanism is not limited to a piston type but can be, for example, a scroll type, a vane type, a helical type or the like.

Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein but may be modified within the scope of the appended claims. 

1. A refrigerant compressor for forming a refrigerant circulation circuit with an external refrigerant circuit comprising: a housing having a plurality of housing components joined together; a compression mechanism provided in the housing, which draws refrigerant gas from the external refrigerant circuit for compression and discharges the compressed refrigerant gas thereto; and an oil separation structure provided on a discharge path of the refrigerant gas flowing from the compression mechanism toward the external refrigerant circuit for separating oil contained in the refrigerant gas, the oil separation structure comprising: a plurality of separation chambers for centrifugally separating the oil from the refrigerant gas; an oil storage chamber for storing the oil separated in the plurality of separation chambers; wherein the plurality of separation chambers and the oil storage chamber are recessed within thickness of a circumferential wall of one of the housing components so as to be juxtaposed in a transverse direction passing across the housing component; a connection passage connecting the plurality of separation chambers, the connection passage extending in the transverse direction along the refrigerant gas flow in the discharge path; and an oil passage connecting the oil storage chamber and the separation chambers, the oil passage extending in the transverse direction.
 2. The refrigerant compressor according to claim 1, wherein the separation chambers includes: a first separation chamber provided on the downstream side of the compression mechanism in the direction of the refrigerant gas flow; a second separation chamber provided on the downstream side of the first separation chamber in the direction of the refrigerant gas flow, the second separation chamber being juxtaposed to the first separation chamber; wherein the first separation chamber has an introduction passage to introduce the refrigerant gas from the compression mechanism, wherein the introduction passage has an opening to the first separation chamber in a position closer to the second separation chamber than a first axis of the first separation chamber; wherein the connection passage connects the first separation chamber and the second separation chamber so as to extend linearly from the first separation chamber toward the second separation chamber, and has two openings to each separation chamber; wherein the opening of the connection passage to the first separation chamber is formed in a position closer to the second separation chamber than the first axis of the first separation chamber; and wherein the opening of the connection passage to the second separation chamber is formed in a position closer to the first separation chamber than a second axis of the second separation chamber.
 3. The refrigerant compressor according to claim 2 wherein the opening of the introduction passage to the first separation chamber and the opening of the connection passage to the first separation chamber are formed in different height positions.
 4. The refrigerant compressor according to claim 2, wherein a cylinder is provided within the second separation chamber for forcedly swirling the refrigerant gas.
 5. The refrigerant compressor according to claim 2, wherein a swirling flow forming member is fixedly accommodated in the second separation chamber.
 6. The refrigerant compressor according to claim 2, wherein a separating portion is provided within the first separation chamber for forcedly swirling the refrigerant gas.
 7. The refrigerant compressor according to claim 1, wherein the compression mechanism is a piston type. 